Einstein's riddle - logic puzzle

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Rating: 3.7/5.0

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There are 5 houses in 5 different colors. In each house lives a person with a different nationality. The 5 owners drink a certain type of beverage, smoke a certain brand of cigar, and keep a certain pet. No owners have the same pet, smoke the same brand of cigar, or drink the same beverage.

Somebody owns a fish. The question is: who?

Hints:

The Brit lives in the red house.

The Swede keeps dogs as pets.

The Dane drinks tea.

The green house is on the left and
next to the white house.

The green homeowner drinks coffee.

The person who smokes Pall Mall rears birds.

The owner of the yellow house smokes Dunhill.

The man living in the center house drinks milk.

The Norwegian lives in the first house.

The man who smokes Blends lives next to the one who keeps cats.

The man who keeps the horse lives next to the man who smokes Dunhill.

The owner who smokes Bluemaster drinks beer.

The German smokes Prince.

The Norwegian lives next to the blue house.

The man who smokes Blends has a neighbor who drinks water.

Explanation

To solve Einstein's riddle, it is useful to make a diagram
which can contain all possibilities, like the one drawn below.
Scroll down to start the interactive step-by-step solution of
the Einstein riddle.

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B-master

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milk

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1. The Brit lives in the red house.

2. The Swede keeps dogs as pets.

3. The Dane drinks tea.

4. The green house is on the left and next to the white house.

5. The green homeowner drinks coffee.

6. The person who smokes Pall Mall rears birds.

7. The owner of the yellow house smokes Dunhill.

8. The man living in the center house drinks milk.

9. The Norwegian lives in the first house.

10. The man who smokes Blends lives next to the one who keeps cats.

11. The man who keeps the horse lives next to the man who smokes Dunhill.

12. The owner who smokes Bluemaster drinks beer.

13. The German smokes Prince.

14. The Norwegian lives next to the blue house.

15. The man who smokes Blends has a neighbor who drinks water.

Start

Click to start the step by step solution
to the Einstein riddle.

Next step

The Brit lives in the red house.
(If we have used all information that a statement contains,
we do not need it anymore and strike it for clarity.)

Next step

The Swede keeps dogs as pets.

Next step

The Dane drinks tea.

Next step

The green house is on the left of the white house.
This implies that the green house cannot be number 5
and the white house not number 1.
There is still information in this statement that
we did not use. Therefore we will need it later on
and do not strike it.

Next step

The green homeowner drinks coffee.

Next step

The person who smokes Pall Mall rears birds.

Next step

The owner of the yellow house smokes Dunhill.

Next step

The man living in the center house drinks milk.

Next step

The Norwegian lives in the first house.

Next step

The man who smokes Blends lives next to the one who keeps cats.

This tells us that the Blends smoker does not keep cats.

Next step

The man who keeps the horse lives next to the man who smokes Dunhill.
So the horse owner does not smoke Dunhill.

Next step

The owner who smokes Bluemaster drinks beer.

Next step

The German smokes Prince.

Next step

The Norwegian lives next to the blue house.

Since we already know that the Norwegian lives in
house 1, the blue house should be number 2. Obviously,
the Norwegian itself does not live in the blue house.

Next step

The man who smokes Blends has a neighbor who drinks water.

So the Blends smoker does not drink water.

Next step

Now we will examine our diagram. We are going to try
whether we can fill in more +'s and -'s. An easy
way to do this is by trying to make (rectangular)
boxes. Every +
has to be an vertex of a box, while a - is an edge.
For this it is convenient to use put +'s in the
boxes claiming that Blends = Blends etc. as well.

Next step

By making a box, we see that the Pall Mall smoker
does not live in a yellow house, is not a German,
is not a Swede, and does not drink beer. We
can fill in 4 -'s

Next step

The Swede does not live in the red house and also not on
number 1. We can put in 2 -'s.

Next step

The Dunhill smoker lives in a yellow
house, does not live on number 2, does not have a horse and also no
birds. He drinks no coffee and no beer too and is
neither a Brit nor a German. We can put in 6 -'s.

Next step

The German, who smokes Prince, does not live on number 1 and
not in a red or yellow house. He does not drink
tea or beer. He has no dogs. We can fill in 5 -'s.

Next step

The man who smokes Blue Master, drinks beer and
is not a Dane, does not live in a green house and not
on number 3. We can put in 3 -'s.

Next step

The man who lives in house 3 and drinks milk
is not a Norwegian or a Dane
and not living in the green house. 3 -'s this time.

Next step

The coffee drinker lives in the green house. He
does not live on number 2, 3 or 5. He
is not a Dane or a Brit. This gives 4 -'s.

Next step

The Dane drinks tea, does not live in a red house and
not in house number 1. He also keeps no dogs.
This gives 3 -'s.

Next step

The Norwegian lives in house 1, which is not blue,
red or white. We can put in 2 -'s.

Next step

The Brit lives in a red house and not on number 2.
Only 1 - this time.

Next step

The owner of the blue house number 2 drinks no milk.
This gives 1 -.

Next step

Now we can use statement 4. The green house cannot be number
1 since it should be left of and next to the white house.
So the green house has to be number 4.
Consequently, the white house is number 5,
the yellow one number 1 and the red house number 3.

Next step

The Norwegian lives in the yellow house number 1
and hence smokes Dunhill.

Next step

Now we can see that the Norwegian drinks
no coffee, no beer, no milk and no tea. He
therefore has to drink water.

Next step

Since the Norwegian who lives in house 1,
drinks water, statement 15 tells us that
the one who lives in blue house number 2 smokes Blends.

Next step

The Brit lives in the red house number 3 and drinks milk

Next step

The Brit lives in house 3, so it smokes either Pall Mall or
Prince. But since he also lives in the red house, he smokes
either Pall Mall or Blue Master. Therefore the Brit
smokes Pall Mall.

Next step

Since the Brit smokes Pall Mall, he rears birds.

Next step

It now automatically follows that the Swede who keeps dogs
smokes
Blue Master and lives in the white house, which is number
5. Consequently he drinks beer.

Next step

The coffee drinker
smokes Prince and is a german. Hence the German lives on number 4.

Next step

The Dane lives in the blue house number 2, drinks tea and smokes Blends.

Next step

Now we will use statement 10. The owner of house 2 smokes Blends.
His neighbour on number 3 rears birds. So the owner of house 1,
which is the Norwegian, keeps cats.

Next step

Finally we will use statement 11. The man who keeps the
horse lives next to the one who smokes Dunhill, which lives
on number 1. So the Dane who lives on number 2 has a horse.

We have solved the Einstein Riddle!

Consequently, the German who lives in the green house
number 4, drinks coffee and smokes Prince, owns the Fish! We have solved
the Einstein riddle.